Assay of human gastric mucin as a natural antibiotic against Helicobacter pylori

Helicobacter pylori infects more than half of the world's population and is considered a leading cause of peptic ulcer and gastric carcinoma. Although a large number of persons are infected with H. pylori, only a limited number of those infected (approximately 3%) develop peptic ulcers and gastric carcinoma. The progression of the disease is restricted by deeper portion of the gastric mucosa, and in many persons glandular atrophy appears to be prevented by mucins secreted in the deeper portion of the mucosa. Recent studies have shown that this inhibitory activity is at least partly due to the expression of alpha 1,4-N-acetylglucosamine residues attached to the mucin (MUC6) in the deeper portion of the mucosa. alpha 1,4-N-acetylglucosamine residues inhibit cholesterol ce-glucosyltransferase, the product of which constitutes a major component of H. pylori cell wall. This inhibitory activity is thus regarded as a natural antibiotic function. This chapter describes the assay for antibiotic activity of MUC6 mucin against H. pylori infection and growth as well as inhibition by alpha 1,4-N-acetylglucosamine-capped mucin-type oligosaccharides.